Design a synchronous counter which takes one bit input X. When X is 1 the counter is counting and incrementing each clock cycle, when x is 0 there is no increment.
You can use a combinatorial black box of increment by 1.
Synchronous Counter
VLSI Interview Questions
it is not clear how to design the circuit without the dimension of the counter. 2 to the power of n.
in the answer they took a counter that count to 16 for example